It is well known that airborne pollutants pose serious health risks when inhaled. Depending on the type of particles inhaled, exposure to airborne pollutants over long periods of time can cause serious illness such as asthma, respiratory disease and lung cancer. Therefore, it is desirable to measure the concentration of dangerous inhaled aerosols in areas suspected of having a high concentration of pollutants.
It is also known that the particle size of airborne pollutants determines the location and amount of material deposited in the lung. These two characteristics are critical to the risk of airborne pollutants. Thus, it is not only important to know the concentration of airborne pollutants, but also to know the size distribution of those pollutants.
One device for capturing particles in the air is a cartridge personal sampling impactor as disclosed in U.S. Pat. No. 4,827,779 to Marple et al. which is incorporated herein by reference. The device includes a housing with an impactor and a filter therein. Air is drawn into the device through one or more inlet holes by a pump attached to the outlet of the device. Large particles in the air are removed by the impactor and any remaining particles are contained by the filter for subsequent analysis. Advantages of this device are that it is small, inexpensive and may operate for long periods of time. It may be placed out of the way in a specific area to capture the airborne pollutants in that area or it may be carried by a person to capture all air pollutants encountered by that person. One major drawback of this device is that it cannot produce an integrated size distribution, in other words, a distribution of the concentration of airborne particles based on size over a long period of time.
There are known machines for measuring particle size and air concentration of inhaled aerosol particles in real time, but these machines are expensive. They are also not robust enough for field or outdoor deployment. Typically, the real time measurements provide only short term data and many measurements would be needed to determine if airborne pollutants pose a long term threat in a suspected “risk” area.
Thus, a device for sampling the size distribution of particles in the air which is inexpensive and operates for long periods of time is highly desirable.